1. Field of the Invention
The present invention relates especially to a method and apparatus for forming a film by using gas deposition process.
2. Related Background Art
Here, first, the gas deposition process will be described in brief. FIG. 3 shows an outline configuration of a film forming apparatus using the gas deposition process. In FIG. 3, this gas deposition process employs an apparatus comprising an ultrafine particle (grain) producing chamber 1, a film forming chamber 2, a conveying pipe 3 or the like. With the ultrafine particle producing chamber 1, a material 8 is heated by using an arc (arc electrode 5), resistor heating, high frequency wave induction heating, laser radiation or the like in the atmosphere of an inert gas.
And, metal ultrafine particles produced by melting, evaporation (gasification) and collision with the inert gas are guided through the conveying pipe (conveying system) 3 to the film forming chamber 2 by means of the pressure difference between the ultrafine particle producing chamber 1 and the film forming chamber 2. And, by high-speed jet from a nozzle 4 connected to the end of the conveying pipe 3, a pattern is depicted directly on a substrate 10 over a stage 9. Incidentally, in FIG. 3, Reference Numerals 6 and 7 denote a pump and a helium gas, respectively.
This type of dry film forming process is known in Japanese Patent No. 2524622, 1595398, 2632409 or 2596434.
Besides, ultrafine particles (grains) are defined to be particulate invisible to an optical microscope, i.e. grains of 1 xcexcm grain size or smaller (Vacuum Handbook, p.289 (Nippon Shinku, Ltd.)). In such a gas deposition process, a film thickness control method is generally to stabilize the material evaporated amount, i.e. ultrafine particle (grain) produced amount and to regulate the travelling speed of the stage holding a substrate. To keep this material evaporated (produced) amount constant, the high-frequency wave induction heating process generally monitors the crucible temperature from the window of the ultrafine particle producing chamber by using a pyrometer or the like and control the electric source power so as to always keep it constant.
Especially in case of heating a material by the arc heating, however, monitoring the temperature of a material by using a pyrometer or the like is extremely sensitive to the place of the material and convection occurs in the melting portion. Under such circumstances, it is extremely difficult to control the arcing power.
Besides, for the arc heating, a constant evaporated amount is theoretically obtained if the value of current, the value of voltage or a material-arc electrode distance can be kept constant. Actually, however, it is substantially impossible to keep these constant continuously because an electrodes tip is deformed on account of melting or the like of an arc electrode. In this point of view, especially as shown in Japanese Patent Application Laid-Open No. 12-17427, it is intended to keep the arc voltage constant and to stably form ultrafine particles. In the case of arc discharge, however, the gap between the electrode and the material widens with the lapse of time on account of melting of an arc electrode and the voltage does not fail to rise as mentioned above.
Such being the case, even if an attempt is made to contract this widened gap and to keep the voltage constant, the initial gap and voltage are not recovered because the electrode surface is deformed rounder. If the gap is forcibly contracted to recover the initial voltage, both of them come into contact with each other and the discharge never fails to end. Besides, if a current is raised so as to keep the voltage constant, the evaporated amount never fails to increase than initial. In such a manner, it is difficult with the arc heating to keep the evaporated amount constant or to control the one.
It is an object of the present invention to provide a film forming method, a film forming apparatus and a manufacturing method of ultrafine particle films as implementing an effective and proper film thickness control.
The present invention relates to a manufacturing method of ultrafine particle films using the gas deposition process including: guiding metal ultrafine particles produced in an ultrafine particle producing chamber together with a carrier gas through a conveying pipe to the film forming chamber; and forming a film on a substrate installed over a stage in the film forming chamber through a nozzle; characterized by using either the intensity of the emission spectrum intrinsic to an evaporation material or that of the emission spectrum intrinsic to the carrier gas or else by using both of these to control the evaporated amount of the above evaporation material and the thickness of a formed film.
Besides, the present invention relates to a film forming method including the steps of: evaporating a source material; bringing a gas different from the above source material into contact with the above evaporated source material to granulate the above evaporated source material; and conveying the grains together with the above gas and colliding them onto a substrate to form a film on the substrate, characterized by controlling the evaporated amount of the above evaporation material and the thickness of a film formed on the above substrate on the basis of the emission spectrum intensity intrinsic to an evaporation material produced in gasifying the above source gas and/or and the one intrinsic to the above carrier gas.
Besides, the present invention relates to a film forming apparatus including: means for gasifying a source material; means for ejecting a gas different from the above source material so as to coming into contact with the above evaporated source material to granulate the above evaporated source material; means for conveying the grains together with the above gas to collide them onto a substrate; and means for controlling the position of the above substrate, characterized by the provision of spectrum detection means for detecting the emission spectra of the above gasified source material and condition control means for controlling the conditions for gasifying the above source material to form the above grains on the basis of the detected value of the above spectrum detection means.